Mrs May also faced questions for the first time over whether she will resign if the Tories lose seats next Thursday, after a rogue poll predicted voters could deliver a hung Parliament.

Dodging the question, she insisted: “There is only one poll that matters and that’s the poll that takes place on June 8 and when it comes to that poll people have a very clear choice and that choice is about who is going to be the Prime Minister”.

The Tories were given a boost last night when the Financial Times became the first national newspaper to give the party its endorsement.

The paper for business bosses has previously switched between Labour and the Tories in past elections, but it declared last night: “Faced with such uncertainty at home and abroad, Mrs May is the safer bet”.